ML Servomotor - Mavilor

CONTENTS1 Introduction2 Ocean Energy Permanent-Magnet3 Feria Electronic Americas 2005JULY 2005ML ServomotorFLAT GEOMETRYAXIAL MAGNETIC FLUXHIGH SPEEDFAST RESPONSE IN A SMALL SIZE4 Typical Servomotor Application5 Mavilor World DistributorsINTRODUCTIONIn this edition of Mavilor Express we will betaking a look at a research project in waveenergy extraction that is currently being doneby researchers at Oregon State University. Thisresearch is being carried out with the help of aMavilor brushless AC servo motor.In the following article we offer readers the newsfrom the recent trade fair that Mavilor had thepleasure of participating in this April in Brazil.Representing Mavilor at Feria ElectronicAmericas 2005 in Sao Paulo were FrancescCruellas, Enric Ciurana, and Miguel AngelRodriguez. The trade fair provided a greatopportunity for Mavilor to make importantcontacts with companies in Brazil and 30 othernations mainly in the Americas.Lastly, Enric Solsona has contributed an articlewhich explains the start/stop process of atypical servomotor application. Hedemonstrates how the use of a Mavilorservomotor can achieve a significant increasein production rate.Thank you, the Mavilor team.MAVILOR MOTORS, S.A.Polígono Industrial URVASA,E- 08130 Santa Perpètua de Mogoda (Barcelona) SpainTel. +34 93 574 36 90 - Fax: +34 93 574 35 70website: www.mavilor.es - e-mail: mavilor@mavilor.es

Ocean Energy Permanent-Magnet,Rack and Pinion Generator BuoyResearchers at Oregon State University (OSU) have identified significantopportunities and benefits from wave energy extraction. The combinationof key OSU facilities, ongoing successful wave energy research, and thetremendous wave potentials off the Oregon coast has led Drs. Annettevon Jouanne and Alan Wallace to propose hosting a U.S. Ocean EnergyResearch and Demonstration Center.OSU is the prime location to conduct ocean energy research, noting the following strategicfacilities:Motor Systems Resource Facility (MSRF)O.H. Hinsdale Wave Research Laboratory (WRL)· OSU is the home of the nation's highestpower university-based energy systemslaboratory, with a 750kVA dedicatedpower supply and full capabilities toregenerate back onto the grid.· OSU is the home of the O. H. Hinsdale WaveResearch Lab (WRL) with world-class wavetank facilities including a 342 ft. wave flume.2

Mavilor Express - Núm. 28 - July 2005A Mavilor brushless ACservo motor provided by InfranorInc. is contributing to the testingof a permanent-magnet, rack andpinion gearbox (PMRPG) systemdesigned to allow generators torespond directly to themovement of the ocean, withcoupling by magnetic fields forcontact-less mechanical energytransmission. Whileconventional electric generatorsare rotary, the motion of a buoyin the ocean is linear andoscillatory (i.e. up and down). Inthe mechanical world,conversion from linear to rotarymotion (or vice versa) can beachieved by a rack and pinion(e.g. the steering system of acar): this requires physicalcontact of the teeth of the pinionwith those of the rack. Incontrast, for this buoy, contactlesstransmission and linear torotary conversion is beingdeveloped as an extension of aconcept of permanent magnetgears. In this device the rotaryspeed of the pinion is greaterthan the linear speed of the rackmaking the output more effectivefor rotary generators (see figuresbelow). This gearing-uptechnique is obtained by aprocess of magnetic fieldmodulation.Concept for Permanent Magnet Rack and PinionGeneratorPermanent Magnet Rack and Pinion Buoy drivenGenerator (designed and now under constructionin MSRF)3

FERIA ELECTRONIC AMERICAS 2005SAO PAULO (BRAZIL) from the 25th to the 29th of April,2005Mavilor has participated with ICEX (INSTITUTE OF SPANISH COMMERCE ) inthis Trade Fair, forming part of the Spanish pavillion.The FIEE 2005, the 23rdInternational Electrical Energyand Automation Industry TradeFair has taken place at anopportune moment for theBrazilian electro-electronicindustry. In 2004, the electroelectronicindustry reached ahistoric growth ratio, with a 28%increase over the previous year.This factor contributed anincrease of 10% in the numberof exhibitors who participatedin this year´s trade fair.Exhibitors from 30 countrieswere brought together for FIEE2005, which demonstrates thepotential for growth in Brazil inthis market. Last year itachieved a turnover of R$80(US 29) billion, which was anincrease of 11% from 2003.Considering that this industrialsector is present in almost allproduction activities in Brazil,we expect that the businessstarted and developed duringthis year´s trade fair will exceedeven the success of last year´sevent. Organizers of the fairhave again managed to createa great setting for exchangingexperiences and doing bigbusiness.Regarding the motion controlsector, Brazil is a huge growingmarket looking for newopportunities. Now, companiesare looking for new products toenlarge and improve theirbusiness activity and this isproven by the changes that arehappening in this sector duringrecent years.Mavilor Motors, S.A. came tothe FIEE trade fair looking fornew distributors and to createa network of after sales serviceproviders in order to improvethe service given to the presentcustomers that already exist inBrasil.The commercial structure thatMavilor Motors S.A. wants tocreate in Brazil consists of:· Having three distributors,one for the Sao Paulo4

Mavilor Express - Núm. 28 - July 2005State, another for MinasGerais State and the thirdone for the southernregion, which will beParaná, Santa Catarina orRio Grando do Sul States.· Create a network ofauthorized independentafter sales providers, whoonce having received thenecessary training in ourproducts, will be able tosupport our customers inBrazil.Another of Mavilor's targets forthis trade fair was to attractnew customers to enlarge ourbusiness in this huge country.We could say that MavilorMotors, S.A. has had asuccessful trade fair, thepresence of Mavilor Motors,S.A. has been very positive, inthe sense that a lot of goodcontacts have been made, andpeople showed a lot of interestfor our servomotors.Now we do not have time tolose. It is time to work hard tobe as present as possible in theBrazilian market.5

TYPICAL SERVOMOTOR APPLICATIONby Enric SolsonaThis article offers an indepth explanation of theadvantages of servomotors for high dynamic duty cycleas beverage labels.START STOP PROCESSSTART requires an accelerationfrom 0 rpm until a speed (S)regime is achieved.STOP requires a decelerationfrom the nominal speed to 0 rpm.PROCESS can be for example:- filling and packing- cut-to-length- plastic bag production- insertion- pick & placeCYCLE TIME =TRANSFER TIME+ PROCESS TIMEFrom the servo system it is notpossible to reduce the processtime. However it is possible toreduce the transfer time for theapplications where the cycle timeis a premium.The Transfer Time Reduction ispossible if:- acceleration time isshorter- running speed is higher- deceleration time isshorter- all the above occurs.To achieve short acceleration anddeceleration times it is necessaryto consider the transmissionmechanism. In ideal conditions,the inertia of the motor, this isthe difficulty to change from onedetermined speed to anotherone, must match the inertia of theload.Note: as inertia of the motor wemust consider the rotor and otherelements mounted on the motor'sshaft such brake or feedbackdevice, although for quickestimations only the rotor's inertiais considered.In order to highlight the dynamicresponse of the motor, we willherein consider that the motorsare applied in ideal inertiaconditions.The typical pattern of the speedtimecurve in a cut-to-lengthapplication is:rpmA(fig.1)Fig. 2 describes in advance thecase described below:trpm(fig.2)The area A equals to space,distance. This can be achievedfollowing both patterns, althoughin high demanding dynamicresponse applications (fig.2) is themost commonly used.When we apply this to a specificcase, like cut-to-length of labelsfor beverages, we come to someinteresting conclusions.tExample:The Marketing Department at abeverage company requireslabels are in the range of 35mm,and the sheets containing thelabels to be cut to length, looklike in the following sketch:In these conditions, 1 revolutionof the wheel driven by theservomotor equalsL = 157,08 mm.DATA: Requested productionoutput: 50.000 bottles / h.Paper length run per hour:50.000 * 0,035 m = 1.750meters / hour à approx. 0,5m/s.Cycle time: 0,035 / 0,5 = 70miliseconds.Out of this cycle time, we willconsider 60 miliseconds for thecutting operation, and theremaining 10 miliseconds are6

Mavilor Express - Núm. 28 - July 2005for accelerating and deceleratingbefore stopping for a new cut.In order to ensure 5 milisecondsfor the acceleration, the timeconstant of the motor must be ofaround 2 miliseconds, andtherefore, the maximum theoreticalacceleration 157.000 rad/s2.Let's take a usual AC brushlessservomotor around 750W or1.000W. In reality can be smallerof 200W or as big as 2,0 kW, sameapplies when comparing theMAVILOR servomotors to others.It is frequent that the MAVILORcompetitors' motors have timeconstants in the range of 10 ms,for what the approximate timerequired to achieve 100% value ofa set speed is at least 15miliseconds.speed(rpm)3.0001.3382.5 ms5 ms50 ms time (s)Would the label be shorter, insteadof 35 mm as per the aboveexample, the limitations due to poordynamic response motors are stillmore evident.For labels 35mm high, a linearspeed of 0,5 m/s requires a totaltransfer time of 10 ms, which is notachievable unless the servomotor'stime constant value is close to 2ms.D = label lengthSpeed 2.675 r.p.m.= 280 rad/s.D = (speed * time) / 2 = [280 rad/s* 0,01 s * 157,08 mm/ 2*pi rad]/2 = 35 mm.RECAPITULATION-The application requires a transfertime of 10ms for 35mm labels-A servomotor of 10ms responsetime would not achieve more than1.338 r.p.m. and the distance runin 10ms would be 8,75 mm < 35mm. Not suitable, in this case.FACTORS AFFECTING THE TIMECONSTANT VALUEThe mechanical time constant iscalculated followingInertia *RMechanical time constant =Kt*EMF constantWhere: R is the winding resistancein ohm, and Kt is the torqueconstant.Motors with a design such thatthey deliver the same outputtorque as other motors but witha smaller frame size, will offeran inertia lower than biggerframe size motors and a lowertime constant. Equally, motorswith a higher resistance valuewill result in a higher timeconstant.Motors with a higher resistancevalue, increase the losses due tovoltage drop, for what theeffective voltage is lower thanfor less resistive motors, andtherefore the EMF constantvalues must be kept low in orderto achieve speed values of 3.000r.p.m. or higher.This has a negative effect againon the mechanical time constant.SOME CONCLUSIONSThe resulting cycle time as transfertime + process time variesdepending on the transfer time,because the process time is fix.Necessary cycle time = 10 ms +60 ms = 70 ms.Production rate: 3.600 seconds/ 0,07 seconds = 51.428bottles/h > 50.000 (correct)Production rate with a poordynamic performance motor of20ms + 60 ms = 80 ms.600seconds / 0,08 seconds =45.000 bottles/h < 50.000 (notcorrect)A MAVILOR servomotor wouldhelp achieving the productionrate, with an additional 14%output compared with the longerresponse time motor.In our example, the potentialCustomer is confronted to thefollowing situation:-He has bought the motoraccording to what he foundavailable in the catalogue: 100W,200W, 400W, 750W, 1,0kWbrushless servomotors-The above powers are related toa rated speed of 3.000 r.p.m.However the motor reaches1.338 r.p.m., which means thatwith a similar rated torque thereal output power is 50%. Thesekind of applications are highdynamic response oriented.The MAVILOR servomotors 220VAC up to a rated power of 3,0kWat 3.000 r.p.m. have timeconstant values of less than 2,5miliseconds.The acceleration required toreach 3.000rpm in 10ms, forinstance, is 31.400 rad/s2,and for 2ms like the mentionedMAVILOR servomotors, inexcess of 150.000 rad/s2.7

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